Nuclear magnetic resonance well logging tools are vitally important to oil field service companies in efforts to obtain extraction of hydrocarbons from geological stratum. Nuclear magnetic resonance well logging tools use specially made arrangement magnets to investigate the geological stratum to desired operating conditions. As a result, different well logging tools may be used if there are different desired depths of investigation.
Nuclear magnetic resonance well logging tools are expensive to produce, however it is important to produce these well logging tools at an economical total cost. One of the most significant aspects of the cost of nuclear magnetic resonance well logging tools is creation and arrangement of magnets in the tool. Reduction of the waste resulting from magnet creation provides significant cost savings.
Placement of magnets in a nuclear magnetic resonance well logging tool is conventionally performed using specially designed magnets. These magnets, however, are not optimal in their overall performance. As a result, static magnetic field (B0) produced by conventional, well logging tools deviates from the original design. This imperfect magnetic field distribution may produce a distorted nuclear magnetic resonance signature during use of the well logging tool.
In an attempt to produce a more consistent static magnetic field, manufacturers attempt to control the overall static magnetic field by adding shims to the magnetic material package. These shims, coupled with removal of magnetic material, for example, can influence the overall static magnetic field delivered by the nuclear magnetic resonance tool. Problems with this type of arrangement abound. Careful mapping and determination of the strength of magnets being installed in the tool must be accomplished in order to determine the field strength. Placement of shims inside a tool, additionally, takes up vital space in the inside of the tool that could be used for more practical purposes.